Is this 7 or 8 days?

I will be arriving at Narita airport on November 15, and heading immediately to Osaka University (staying near the Ibaraki station) to attend a week-long conference. Given the local bus travel in the Osaka region, I plan on getting an IC card to cover my travel expenses until I return to Narita on November 22.

By my math this is 8 days and would require a 14-day pass, which is more expensive than buying the tickets individually. I want to confirm that I am counting correctly, and that I could not do this with a 7-day pass.